This invention relates to a composition for use in the production of foamable sheet material, which sheet material may be fabricated into carriers, for attachment to cylindrical containers.
More specifically, the invention relates to a composition which provides a reduction in weight to the sheet material without a corresponding reduction in specific properties of the fabricated carrier.
Carriers used heretofore for attachment below the chimes of cylindrical containers have seen wide spread use by industry and have gained wide acceptance by the consuming public. The light weight character and durability of plastic carriers have provided numerous advantages over paper carriers. However, minimum thickness levels for unfoamed sheet material for fabrication into carriers and handability by machines is required, and the properties of the sheet material were more than necessary.
To overcome the problem of "wasting" properties and/or having to alter machinery to handle thinner sheet material, attempts have been made to moderately or heavily foam the sheet material. As anticipated, another problem arose regarding degradation of properties, such that the carriers produced were not suitable for use, especially with regard to tear propagation properties.
The lightly foamed sheet material of this invention has properties within the specifications required of unfoamed sheet material as a carrier for cylindrical containers. It is lighter in weight, it reduces raw material requirements and provides enhanced tear properties over unfoamed or moderate/heavily foamed sheet material.
One advantage then of the present invention is that a lighter weight sheet material is formed which is usable in the fabrication of carriers for cylindrical containers on existing equipment, without a corresponding loss in properties.
Another advantage of the present invention is the reduction in the amount of raw materials per sheet material or carrier produced.
Yet another advantage of the present invention is improved tear resistance and resistance to propagation of tears once commenced for the sheet material or carrier produced.
One feature of the present invention is the use of a blowing agent mixture to obtain the foamed, lighter weight sheet material when the composition is extruded on existing equipment.
Still another feature of the present invention is that scrap sheet material, obtained during fabrication of the carriers can be chopped and reused in the composition without adversely affecting the properties or performance of the carrier.